If you are decorating, you may want to remove the radiator to decorate behind it.
A system left idle for some time can suffer from a build up of sludge at the bottom of the radiator.
For any of these reasons the job can be done without draining the whole system.
Make sure you have some rags or dustsheets beneath the radiator before you begin. The
control valve can be closed off by hand. Next close the lockshield valve with a small
spanner (or pliers). It is worth noting the number of turns required closing it, as this
same number can be applied when opening it again. As the water from the radiator needs to
run out, place a bowl under the control valve before disconnecting the union nut. It is
best to have a second container ready in case there is too much water for the bowl in place
to cope with. The air vent at the top should be opened to increase the water flow. Once it
stops running out, undo the union nut on the lockshield valve. There may be more water
flowing out at this stage, so be prepared. Use some pieces of old rag or twisted pieces
of paper to block the open ends before lifting the radiator off the brackets. Keep the
radiator upright and carry it outside.
If you are decorating, you can complete the task, being careful not to interfere with the
valves.
If you are going to replace the same radiator, flush out any sludge and clean it outside
before bringing it back into the room for re-fixing. It is worth checking the wall brackets
are still secure on the wall before replacing. Place the radiator back on the wall brackets
and reconnect the union nuts. When you open the valves, the water will start to fill the
radiator with water again. Make sure the air vent is open to allow the air to escape. Check
the area underneath for any leaks and reset the lockshield valve into position.